A review of the health-related quality of life and economic impact of Parkinson's disease.

Parkinson's disease (PD) is a chronic, neurodegenerative disease that places a substantial burden on patients, their families and carers, as well as on society as a whole. PD can severely affect the health-related quality of life (HR-QOL) of both patients and their carers and, as the disease progresses, HR-QOL deteriorates. This review aims to critically evaluate the literature on a number of important aspects that influence HR-QOL in relation to PD. Factors associated with a negative impact and ways to improve HR-QOL are highlighted, and tools for HR-QOL assessment reviewed. The economic impact of PD and related cost-effectiveness studies are also reviewed. Over the course of the disease, patients with PD experience changes in their HR-QOL that are affected by factors such as depression, motor complications, education and surgery. However, a lack of uniformity in the choice of HR-QOL tools used in studies makes comparison of results difficult. Research on motor fluctuations and dyskinesias has shown conflicting results, whereas it is clear from the available data that depression needs to be more clearly recognised and treated. Inequality in the numbers of men and women receiving surgery still needs to be addressed and, again, in this area there is a lack of uniformity with respect to assessment for surgery. Education programmes have been shown to be successful in improving HR-QOL, although more research is needed about how to introduce such programmes to all PD patients. In particular, there has been little detailed research into young-onset PD and juvenile patients to assess the true impact of the disease on their HR-QOL. The literature has also shown that PD can affect the HR-QOL of the carer, which may have a 'knock-on' effect for the patient. The HR-QOL of carers needs more attention because these individuals can significantly reduce the burden that would otherwise fall on the health services in terms of cost and care. Research shows that the economic costs of PD are high, particularly for patients in advanced stages of the disease and those with motor complications. Although carer burden is a major source of costs, this is not factored into cost-effectiveness analyses. Furthermore, because too few studies use quality-adjusted life years as their health outcome, particularly in studies of the costs of surgery, comparison of costs of treatments is difficult. The review highlights the need for HR-QOL tools such as the EuroQol-5D to be used together with disease-specific tools to provide the most comprehensive picture of the costs and impact of PD.A recent upsurge in published literature on PD resulting from increased interest in HR-QOL issues has led to an at times overwhelming amount of new information. The present review assembles the most important points relating to HR-QOL in PD raised in the literature, adds value to previously covered issues, and examines areas of HR-QOL in PD that have not previously been reviewed, such as education, carer burden and surgery, highlighting where more research is warranted.